The invention relates to a hand-held power tool comprising a work spindle for driving a tool, said tool being fastenable between a fastening element and a holding portion on a tool end of the work spindle, and a displacement device for sliding the fastening element between a released position in which the fastening element can be detached from the work spindle and a clamped position in which the fastening element is clamped against the holding portion by a spring element.
A hand-held power tool comprising a clamping device for manually clamping a tool is known from EP 0 152 564 B1.
Said known hand-held tool is an angle grinder that includes a hollow drive shaft with a spindle displaceably mounted therein. Said spindle can be displaced by a clamping device between a clamped position and a released position. In the clamped position, a tool such as a grinding disk can be clamped against a fastening portion with the aid of a nut and held in the clamped position under the force of a spring after the clamping device is moved. Since the displacement device in the released position causes the spindle to move against the force of a spring, the nut can be screwed off without the aid of an accessory when in the released position, in order to change the tool.
Although a clamping device of this kind basically enables a tool to be clamped onto the drive shaft of a hand-held tool without the need of an accessory tool, such a clamping device is suitable only for clamping tools that are rotatingly driven. If the tool is driven by an oscillating drive means such that it oscillates back and forth about the longitudinal axis of the work spindle, this results in large abrupt torques in both directions of rotation and with great impetus, with the result that it is not possible with the known clamping device to ensure that the tool is clamped sufficiently securely.
Another hand-held power tool is known from DE 198 24 387 A1 that has an oscillatingly driven work spindle for driving the tool. Said tool can be fastened to the work spindle between a holding portion of the work spindle and a fastening flange which is rigidly connected to a clamping bolt. The clamping bolt can be held on the work spindle by means of a collet-like clamping effect, a retaining ring or O-ring, by magnetic force or by means of a locking mechanism in which a spring impinges upon locking roller members.
Although the various solutions known from this document are essentially suitable for clamping a tool onto a work spindle without using an accessory, it has been found that the clamping forces that can be achieved here are likewise inadequate for many applications.